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81 Cards in this Set
- Front
- Back
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What is BK polyoma virus and polyomavirus nephropathy (PVN)
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A non-enveloped DNA virus belonging to the Polyoma virus subfamily of Papovaviridae.
It causes polyomavirus nephropathy. |
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Describe the behavior of BK virus in the body.
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It is a very common, asymptomatic infection (80-90% of the population is positive) - it persistently infects epithelial cells of the urinary tract.
Like herpes viruses, upon immunosuppression, BK virus reactivates and causes disease. |
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Describe polyomavirus nephropathy.
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The BK virus causes an acute interstitial nephritis manifesting as renal dysfunction in 1-10% of renal transplant patients
Graft loss occurs in up to 90% of PVN cases |
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What virus may cause hemorrhagic cystitis in BMT recipients?
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BK Polyoma virus
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How is PVN treated?
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Judicious reduction of immunosuppression regimen
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What pathogen causes hemorrhagic adenovirus cystitis?
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Adenovirus serotypes 11 and 21
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Who gets hemorrhagic adenovirus cystitis? How is it different in transplant vs healthy patients?
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Causes hemorrhagic adenovirus cystitis in renal transplant patients, pediatric BMT recipients, and healthy young boys.
In non-immunocompromised patients, cystitis is limited to a mild, self-limiting disease |
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What are some symptoms of hemorrhagic adenovirus cystitis?
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Urgency
Frequency Dysuria May cause fever, hematuria, dyspareuria, abdominal cramps, and/or bladder pain and spasms |
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What drugs may be used to treat hemorrhagic adenovirus cystitis?
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Vidarabine
Cidofovir Ganciclovir |
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What is HIV-associated nephropathy?
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Patients tend to present with a rapid decline in renal function, with a nephrotic syndrome consisting of proteinuria, azotemia, hypoalbuminemia, and hyperlipidemia.
*Not typically hypertensive* |
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What is the fourth leading cause of death in patients with HIV?
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Kidney disease and renal failure
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What are some problems that may look like HAN?
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Medication toxicity
Volume depletion Sepsis Liver disease-induced causes of renal failure |
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Who is most susceptible to HAN?
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Blacks with a polymorphism in the MYH9 gene (which encodes the non-muscle myosin heavy chain IIA protein) expressed in podocytes - plus HIV infection
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What are the unifying pathological characteristics of HAN?
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Hyperplastic injury within the glomerulus
Podocyte proliferation Glomerular sclerosis Tubular dilatation Interstitial inflammation |
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How is HAN treated?
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Aggressive treatment with HAART; steroids and angiotensin-converting enzyme inhibitors - mortality still reaches about 30%
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How is glomerulonephritis induced by viral infection?
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Cryoglobulinemia - immunoglobulins that precipitate in the cold but are soluble at body temperature. Some can form immune complex diseases.
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What viruses are associated with glomerulonephritis from cryoglobulinemia?
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Chronic viral infections like HIV, HBV, HCV
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How does glomerulonephritis from cryoglobulinemia present?
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Presents as renal disease and small vessel vasculitis, with palpable purpura, neuropathy, and lymphadenopathy
Associated with proteinuria, microscopic hematuria, impaired kidney function |
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What virus causes hemorrhagic fever with renal syndrome?
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Hantaviruses - of family Bunyaviridae
Enveloped ssRNA viruses |
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What are some of the disease entities that cause hemorrhagic fever with renal syndrome?
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Korean HF - Hantaan virus - in Europe and Asia
Seoul HF - Eastern Asia, Japan Nephropathia endemica - Puumala virus - Scandinavia, NW Russia - more mild |
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What kind of renal damage is caused by hemorrhagic fever?
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It causes an acute interstitial nephritis, with tubular necrosis
Pathology is due to damage to vascular endothelium. Mechanism is unknown, but damage may be immune-complex mediated. |
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How is HFRS spread?
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Spread by rodent contact only - aerosolization and inhalation of dried rodent urine or excreta
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What are the symptoms of HFRS?
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Illness may be moderate or severe, with fever, oliguria, proteinuria, abdominal pain, hemorrhaging.
Initial symptoms - fever, flushed face, periorbital edema, palatal and axillary petechiae, conjunctivitis, headache, eye pain, lumbar pain, TTP |
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How is HFRS treated?
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Mortality rate from shock may be > 5%
Ribavirin has been used for KHF Shock is managed with careful fluid replacement A recombinant vaccine is available in Asia for KHF (Hantavax) |
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Give a few statistics about UTIs
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20% of women have one before age 30
50% of women have a UTI at some point in their lives 40% of nosocomial infections are UTIs 25-50% of nursing home patients have bacteriuria at any time |
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What are the two categories for lower urinary tract infections?
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Urethritis - of urethra
Cystitis - of bladder Also considered superficial infections |
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What are the two categories for upper urinary tract infections?
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Pyelonephritis - the kidney
Prostatitis - the prostate Also considered invasive infections |
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What is the major defense mechanism against UTIs?
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Flow of urine - cleanses, acidic
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What is acute uncomplicated UTI?
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Acute cystitis - common in healthy women
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What is acute uncomplicated (non-obstructive) pyelonephritis?
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Kidney infections - common in otherwise healthy women
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What is a complicated UTI?
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Bladder or kidney infections in individuals with underlying structural or functional abnormalities of the genitourinary tract (in men and women)
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What is asymptomatic bacturia?
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Bacteria in the urine without symptoms or signs attributable to UTI.
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What is a renal abscess?
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Uncommon - may occur with severe pyelonephritis or following bacteremia from other site of infection
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Compare the susceptibilities of men and women to developing a UTI.
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Females - higher susceptibility. Shorter urethra, proximity to source of infection, entry of bacteria is facilitated by sexual intercourse
Males - low susceptibility, longer urethra compared to women, antimicrobial substances in prostatic secretion, increased UTIs with prostate hypertrophy. |
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What are some factors that may increase the risk of developing a UTI?
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Renal calculi
Ureteric reflex Tumors in and adjacent to urinary tract Pregnancy, Bladder Stones Neurological problems Incomplete bladder emptying large volume of residual urine Loss of sphincter control Prostatic hypertrophy Short urethra in women Catheterization |
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What are some bacterial factors that increase chance of a UTI?
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Capsular antigens
Hemolysins Urease Adhesion to uroepithelium (P fimbrae in E. coli) Introital colonization |
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What bacteria are most often responsible for uncomplicated UTIs?
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Uncomplicated UTI
E. coli - 80-85% of cases Staphylococcus saprophyticus - 5-15% of cases Other Entereobacteriaceae - Proteus mirabilis, Klebsiella pneumoniae |
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What bacteria are most often responsible for complicated UTIs?
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Complicated (or nosocomial) Infections
E. coli 20% of cases The other 80% include... Enterobacteriaceae - Proteus mirabilis, Klebsiella pneumoniae, Enterobacter, Serratia Pseudomonas aeruginosa Enterococcus species Staphylococcus aureus |
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Describe the distribution of Enterobacteriaceae, and what kind of infections they cause.
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Found worldwide, in soils and water
Normal intestinal flora 70% of UTIs 35% of Septicemias Respiratory tract CNS GI tract |
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What are the microscopic and metabolic characteristics of Enterobacteriaceae?
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Gram Negative Rods
Facultative anaerobes, no spores Motile or Non-motile - may have flagella Simple nutritional requirements, ferment glucose Reduce nitrates to nitrites Catalase Positive, Oxidase Negative They have varying resistance to bile salts and fermentation abilities |
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What is the use of pili in Enterobacteriaceae?
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Common fimbrae (pili) - adhesion to host cell
Sex pili - coded on conjugated plasmids, allows for genetic transfer between bacteria |
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What are some virulence factors of Enterobacteriaceae?
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Exotoxins
Adhesion factors Capsule Antigenic phase variation Type III secretion system Antimicrobial resistance |
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What are the three components of Lipopolysaccharide?
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1 - Outermost somatic O polysaccharide
2 - A core polysaccharide "Enterobacterial common antigen" 3 - Lipid A |
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How does LPS act as an endotoxin?
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Lipid A is released as the cell lyses
It is a sign of systemic gram negative bacterial infections - complement is activated, cytokines released, leukocytosis, role in septic shock. |
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How are Enterobacteriaceae serotypes classified?
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Based on 3 major groups of antigens
O - specific polysaccharides in outer membrane - always present H - flagellar H proteins - motile cells only K - capsular polysaccharide antigens, not always present |
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What are some characteristics of E. coli (microscopy, metabolic)?
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Motile - peritrichous flagella
Ferments lactose Urease negative |
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What are some common infections caused by E. coli?
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UTI
Diarrheas/Dysentery Neonatal meningitis Septicemia |
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What are some of E. coli's virulence factors?
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Adherence - P pilus (Pyelonephritis-associated pilus) binds digalactose receptor on uroepithelial cells
FimH - mannose sensitive pilus - binds mannosylated proteins that line the bladder mucosa Motility Hemolysin - pore forming cytotoxin LPS |
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What are some characteristics of Proteus mirabilis?
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Highly motile (peritrichous flagella)
Does not ferment lactose Urease positive |
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What kinds of infections are caused by Proteus mirabilis?
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Community and hospital-acquired UTIs
Pneumonia Septicemia Wound infections |
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What are some virulence factors of Proteus mirabilis?
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Adhesins
Motility - swarming Endotoxin - inflammatory response Urease production - increases urine pH, which is toxic to renal cells and potentiates the formation of calculi. |
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What are some characteristics of Klebsiella pneumoniae?
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Non-motile
Ferments lactose Urease negative |
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What are some infections caused by Klebsiella pneumoniae?
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UTIs - community, nosocomial
LRTI - lobar pneumonia in infants, elderly, alcoholics, chronic lung disease Often transmitted via catheters |
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What are some virulence factors of Klebsiella pneumoniae?
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Pili - adherence to urinary epithelium
Polysaccharide capsule - interferes with complement activation, antiphagocytosis Endotoxin - causes fever, inflammation |
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What are some characteristics of Enterobacter sp.?
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Motile - peritrichous flagella
Ferment lactose Urease negative Cause nosocomial infections |
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What are some virulence factors of Enterobacter?
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Adhesins
Capsule * Major virulence factor * Endotoxin |
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Where are Serratia sp. found?
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Habitat is the gut of humans and animals, environment as well
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What is the name of the only pathogenic species of Serratia?
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Serratia marescens
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What are some characteristics of Serratia?
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Slow lactose fermenter
Produce a red pigment, distinctive brick-red colonies Cause nosocomial infections |
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What are some virulence factors of Serratia?
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Adhesins
Capsule Endotoxin |
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How is Enterobacteriaceae identified?
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Urine culture
Plate on MAC agar, |
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What are the various Lactose fermenting abilities of E. coli, K. pneumoniae, Enterobacter, Serratia, and P. mirabilis?
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Lactose Fermenters - E. coli, K. pneumoniae, Enterobacter
Slow Lactose Fermenter - Serratia Does not ferment lactose - P. mirabilis |
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What are two additional tests, besides lactose, that are used to identify P. mirabilis?
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Swarming motility test (positive)
Urease test (positive) |
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What are some characteristics of Pseudomonas aeruginosa?
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Aerobic Gram Negative Rod
Motile Oxidase positive No Fermentation Adapt to low nutrients Cause a variety of opportunistic infections |
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What are the virulence factors of Pseudomonas aeruginosa?
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Adhesins - adhere to epithelial cells
Polysaccharide capsule - protect from phagocytosis/opsonization Endotoxin - inflammation Extracellular enzymes and toxins - Exotoxin A - tissue damage |
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How is Pseudomonas aeruginosa diagnosed?
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Microscopy - gram negative rods
Culture - blue-green colonies with procyanin/pyoverdin, fluorescein, grows at 42 degrees, fruity aroma, mucoid, fluoresces |
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What are some characteristics of Staphylococcus aureus?
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Gram positive cocci
Irregular clusters - grapelike Catalase positive Coagulase negative Facultative anaerobe Phosphatase negative Urease and lipase positive S. saprophyticus causes 10-20% of UTIs in sexually active young women |
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What are some virulence factors of S. saprophyticus?
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Transmission - endogenous spread
Adhesin Elicits an inflammatory response |
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How is S. saprophyticus diagnosed?
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Urine culture - growth on blood agar, gamma hemolysis, novobiocin resistant
Gram positive cocci in irregular clusters Coagulase negative |
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What are some characteristics of Enterococcus faecalis/faecium?
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Gram positive diplococci or short chains
Catalase positive Lancefield's group D antigen Facultative anaerobes Most infections from endogenous flora |
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What kinds of infections are caused by Enterococcus faecalis/faecium?
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UTI
Endocarditis Wound infections Bacteremia |
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What are some virulence factors of Enterococci?
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Adhesins
Toxins and enzymes, tissue damage - cytolysin, gelatinase, serine protease All strains carry some drug resistance |
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How is Enterococci diagnosed?
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Urine culture - gamma or alpha hemolytic on blood agar
Resistant to 40% bile salts, 6.5% NaCl, Bacitracin, Optochin Microscopy - Gram positive cocci, short chains PYR (L-pyrrolidonyl-B-naphthylamide) test - to detect presence of pyrrolidonyl peptidase |
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Describe the clinical presentation of Cystitis.
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Generally NO invasion of mucosa, it is superficial irritation
Dysuria Urgency Frequency Urine cloudy Gross hematuria in 50% of cases No fever or systemic manifestation of illness |
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Describe the clinical presentation of Pyelonephritis.
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Invasive disease - may be preceded or accompanied by manifestations of Cystitis
Flank pain, tenderness Systemic manifestations: Fever, chills, more severely ill patients have vomiting, diarrhea, tachycardia |
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What is the clinical presentation of Prostatitis?
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Pelvic and low back pain
Acute infection with high fever, dysuria, frequency Inflammatory swelling - obstruction of urethra and urine retention Chronic prostatitis - low-grade pain and dysuria when symptoms are present, cause recurrent bacteremia in men |
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How are urine samples obtained?
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Clean-void technique - clean area, catch midstream
Catheterization Suprapubic aspiration |
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What lab results are necessary for a positive UTI diagnosis?
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Colony count must be > 10^5 CFU/mL of urine
That is considered infection or "significant bacteriuria" 30-50% of women with acute cystitis have lower counts |
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What microscopy results would indicate UTI?
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90% of patients with acute symptoms of UTI have pyuria
Gram stain |
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What dipstick results indicate possible UTI?
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Positive leukocyte esterase test - tests for the presence of leukocytes in the urine
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How are UTIs treated?
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Antibiotics
Acute uncomplicated cystitis - 3 days TMP-SMZ Acute uncomplicated pyelonephritis, complicated UTI, resistant organisms - Fluoroquinolone 10-14 days, check cultures later Pregnant women - Cephalosporin Complicated UTI - hold off on therapy until cultures come back Increase fluid intake |
